Merge pull request #303 from rethinkdb/srh/requirements

Specify 'coverage' package version in requirements.txt

Author: lsabi

requirements.txt

@@ -1,4 +1,6 @@
 async-generator==1.10; python_version>="3.6"
+coverage<=4.5.4; python_version<"3.5"
+coverage==5.5; python_version>="3.5"
 codacy-coverage==1.3.11
 looseversion==1.3.0
 mock==3.0.5